JPH0262715B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a curve correction method for correcting an outer rotor curve with respect to a theoretical curve in a combination of an inner rotor and an outer rotor of an internal gear pump having trochoid meshing. It is about the method.

[Prior art]

Figure 1 is an explanatory diagram of the theoretical curve of the inner rotor using the trochoid curve, and the basic circle radius AO
When rolling circle 2 with rolling radius BO rolls without slipping on the circumference of base circle 1, the locus drawn by a point separated by eccentricity e from the center of rolling circle 2 is a trochoid curve T,
The radius of the drawing circle centered on this trochoid curve T
The theoretical curve of the inner rotor 4 is obtained from the envelope of the drawn circle 3 of CO, and the number of teeth n of the inner rotor 4 at this time is the basic circle radius AO and the turning radius BO.
is determined by the ratio AO/BO. Outer rotor 5 that meshes with this inner rotor 4
is obtained by a row circle 7 with the same radius CO as the drawing circle 3 on the row circle center circle 6 with radius DO=AO+BO as shown in FIG. 2, and the number of teeth of the outer rotor 5 at this time is n+ for the number of teeth n in 4
It becomes 1. As shown in FIG. 3, internal gear pumps that utilize trochoidal meshing between an inner rotor 4 and an outer rotor 5 within a pump case 11 have recently been widely used as hydraulic pumps and lubricating pumps for internal combustion engines. However, the meshing between the inner rotor 4 and the outer rotor 5 obtained as described above according to the theoretical curve, that is, the meshing with no gap between the inner rotor 4 and the outer rotor 5, is actually difficult due to processing accuracy. This is undesirable in order to prevent malfunctions due to errors in rotation and galling of the rotors 4 and 5 due to particulate foreign matter contained in the fluid being handled, and it is therefore necessary to provide a gap between the inner rotor 4 and outer rotor 5. There is. As a way to create this gap,
In the explanatory diagram of the theoretical curve of the outer rotor shown in Fig. 2, the center circle radius DO of the row circle is corrected.

Correct column circle radius CO.

Do both of the above at the same time.

Attempts have been made to create a gap when combined with an inner rotor using one of the methods.

[Problem that the invention seeks to solve]

In the above modification method, and can be performed relatively easily, but when the combination of the outer rotor 5 and the inner rotor 4 modified by this modification method is used as an internal gear pump as shown in FIG. , inner rotor 4
In order to compress the fluid trapped in the interdental space between the outer rotor 5 and the outer rotor 5, a force is applied to the outer rotor 5 in the direction of the arrow while the pump is rotating.
The outer rotor 5 is pushed and rotated in the direction of the arrow within the gap between it and the pump case 11, and the gap S in the state shown by the broken line in FIG. 3 becomes large, resulting in a decrease in pump efficiency. For this reason, attempts have been made to reduce the maximum gap amount S using the correction method described above.This method can reduce the gap amount S if appropriate corrections are made, but the radius of the row circle center circle DO It is extremely difficult to obtain an appropriate correction because the diameter and radius of the row circle CO are to be corrected at the same time, and trial and error is often repeated each time the tooth profile of the outer rotor is changed. The present invention was developed in view of these points, and it is possible to extremely easily modify the outer rotor curve of a trochoidally meshed internal gear pump, and also improves pump efficiency by reducing the maximum gap amount that occurs when the rotor rotates. An object of the present invention is to provide a method for modifying an outer rotor curve of a trochoidally engaged internal gear pump.

[Means for solving problems]

As a result of repeated analyzes of the rotors of internal gear pumps with trochoidal meshing, the present inventor discovered that if the outer rotor curve is corrected under certain conditions, appropriate corrections can be easily made and the maximum clearance amount can be reduced. Base circle radius AO, rotation radius BO, eccentricity e, drawing circle radius CO, number of teeth n=
Inner rotor whose theoretical curve is given by AO/BO, row circle center circle radius DO=AO+BO,
In combination with an outer rotor whose theoretical curve is given by the row circle radius CO and the number of teeth n+1, the outer rotor center O1 is determined as shown in Fig. 4.
A point P1 that is set back by the basic correction amount ΔX from the outer rotor theoretical curve in the direction of the row circle center O2 on the axis L1 that passes through the row circle center O2 and the row circle center O2 is given by sin α=e/BO from the axis L1 that passes through the row circle center O2. angle α
The outer rotor curve is corrected from the theoretical curve by a circular arc passing through points P2 and P3 that are set back approximately ΔX/2 from the theoretical curve on two lines L2 and L3 that are inclined by ΔX/2. That is, the outer rotor is manufactured by determining the row circle center circle radius D1 and row circle radius C1 of the circular arc passing through the above three points. However, if the amount of retraction from the theoretical curve on lines L2 and L3 of the corrected outer rotor curve is smaller than ΔX/2, there is a risk of interference during rotor rotation, and if the amount of retraction is larger than ΔX/2, there is a gap. The amount S will increase.

[Effect]

In the above correction method, approximately ∆X /2 Since the outer rotor curve is corrected using an arc passing through the retreated points P2 and P3, the outer rotor curve should be corrected using an arc passing through the three points according to the above conditions for any outer rotor tooth profile. For example, the outer rotor curve can be appropriately modified to reduce the maximum clearance amount very easily.

〔Example〕

The above correction method is as follows: base circle radius AO = 30mm, rolling circle radius BO = 7.5mm, eccentricity e = 4mm, drawing circle radius CO
= 20 mm, number of teeth n = 4 as the theoretical curve, inner rotor and row circle center radius DO = 37.5 mm, row circle radius CO
The test was carried out using an outer rotor with a theoretical curve of = 20 mm. First, the basic correction amount ΔX on the axis passing through the outer rotor center O1 and the row circle center O2
= α given by Sin α = e/BO = 0.53 from the axis passing through the point P1 set back by 0.05 mm and the row circle center O2
=32.2゜From the theoretical curve on the inclined line ΔX/2=
Find an arc that passes through points P2 and P3 that have retreated by 0.025 mm, and find the corrected row circle center circle radius D1 and row circle radius C1 based on the center and radius of this arc.D1
= 37.72mm and C1 = 20.179mm are given, and the outer rotor is manufactured using this. FIG. 5 shows the results of measuring the gap S between the outer rotor and the inner rotor. The measurement conditions were as shown in Figure 3, where the outer rotor was pressed in the direction of the arrow and the amount of gap S accumulated on one side was measured. The amount S was measured. In FIG. 5, S3 in the figure is a diagram showing the gap amount S according to the correction method of the present invention, and S1 in the figure shows the basic correction amount ΔX=0.05mm for the row circle radius CO that has been tried in the past.
A diagram showing the clearance amount S in combination with the outer rotor that has been reduced to 19.95 mm,
In the figure, S2 is a diagram showing the clearance amount S in combination with the outer rotor, which has been corrected to 37.55 mm by increasing the basic correction amount ΔX=0.05 mm to the row circle center circle radius DO of the outer rotor, which has been attempted in the past. From this result, in the conventional correction methods shown as S1 and S2 in the figure, the clearance amount S is large at S1 = 0.168 mm and S2 = 0.154 mm when the rotor rotation angle is 0°, whereas In the modification method of the present invention shown as S3, the clearance amount S is reduced to 0.122 mm when the rotor rotation angle is 0°. That is, the present invention corrects the outer rotor curve using an arc passing through three points determined from the theoretical curve, which is an extremely easy method, yet provides appropriate correction and reduces the maximum gap amount.

[Effect of release]

Since the present invention is as described above, in the method for modifying the outer rotor curve of a trochoidally meshing internal gear pump, if the present invention is applied to any tooth profile of the outer rotor, appropriate modification can be obtained very easily. The maximum gap amount can be reduced.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the theoretical curve of the inner rotor, Fig. 2 is an explanatory diagram of the theoretical curve of the outer rotor, Fig. 3 is a front view of the internal gear pump, and Fig. 4 is the outer rotor curve correction method of the present invention. FIG. 5 is a diagram showing the relationship between the rotor rotation angle and the gap amount. Explanation of symbols, 1...Basic circle, 2...Rotated circle, 3
... Drawing circle, 4 ... Inner rotor, 5 ... Outer rotor, 6 ... Row circle center circle, 7 ... Row circle, AO ... ... Base circle radius, BO ... Turning circle radius,
CO...Drawing circle radius, e...Eccentricity, T...Trochoid curve, CO...Run circle radius, DO...Run circle center circle radius.

Claims (1)

[Claims] 1 Base circle radius AO, rotation radius BO, eccentricity e,
Inner rotor whose theoretical curve is given by drawn circle radius CO, number of teeth n = AO/BO, row circle center circle radius DO = AO + BO, row circle radius CO, number of teeth n +
In combination with an outer rotor whose theoretical curve is given by Passing through O2 and from the axis
The outer rotor curve is corrected from the theoretical curve by an arc passing through points P2 and P3 that are set back approximately ΔX/2 from the theoretical curve on a line inclined by an angle α given by sin α=e/BO. A method for modifying the outer rotor curve of an internal gear pump with trochoidal meshing.